Power-operated pneumatic tool



sept. 5, 1939. A. PALMRos POWER-OPERATED PNEUMATIC TOOL lOriginal Filed Nov. 13, 1956 2 Sheets-Sheet l w .mm

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Sept. 5, 1939. A. PALMROS 2,171,946

PowER-oPERATED PNEUMATIC TooL original Filed Nov. 1s, 195e shams-sheet` 2 INVENTOR i Patented Sept. 5, 1939 UNITED STATES PATENT OFFICE' Alexander Palmros, Rochester, Pa. V

- Application November 13, 1936, Serial No. 110,676

Renewed February 1, 1939 1s claims. (o1. 12s-34) My invention relates, generally, to poweroperated pneumatic tools of the percussion type, and, more particularly, to tools such as pavement cutters, rock drills, tampers, pile drivers, and the like, wherein a power source in the form of a. motor or engine is utilized to actuate a working piston which produces and controls the duid-pressure such, for example, as air pressure, to actuate a oating hammer member.

The object of my invention, generally stated, is to provide a fluid-pressure-percussion tool which shall be oi relatively simple and light-weight construction, economical and eiicient in operation and which may be readily and economically manufactured.

A more specific object of my invention is to provide for utilizing a motor or engine for actuating the working piston in a fluid-pressure percussion tool through the agency of a crank-driven crosshead.

Another object of my invention is to provide for utilizing oppositely rotating cranks for imparting a reciprocatory motion to a crosshead for actuating a piston.

A further object of the invention is to provide for actuating the working piston in a fluid-pressure tool by means of oppositely driven rotatable gear members arrangedto reciprocate a cross.- head attached to the piston.

A still further object of my invention is to provide for actuating a reciprocatory crosshead member by means of a motor or engine nzsuch manner that balanced'driving forces are always applied to the crosshead member.

Another object of my invention is to provide a fluid-pressure operated tool in which the fluidpressure is released from a pressure chamber by the action of the working piston.

Another object of my invention is to provide for controlling the fluid-pressure in a tool of this character by means of a valve which is actuated in accordance with the position of the working piston.

A further object of my invention is to provide afluid-pressure actuated tool having a working piston and a oating hammer Within a common cylinder wherein the piston is utilized to produce pressure and to actuate a valve to release the pressure to actuate the hammer.

These and other objects of my invention will become more apparent from a study of the iollowing detailed description, in conjunction with the drawings, in which: y

Figure l is a sectional view of a device'embodying the principal features of the invention;

Fig. 2 is a sectional view of the transmission casing showing the crosshead;

Fig. 3 is a View of the tool chuck; Fig. 4'is a plan View of the crosshead showing the opposed paths of movement of the cranks; 5 and Fig. 5 is a partial sectional View of the device illustrated in Fig'. 1 showing a modification thereof.

` The principles of the invention will be de- 10 scribed inA connection with their application to a pavement cutter, although it is to be understood that the invention may be as readily utilized in tools of other kinds.

In practicing myinvention in its preferred 15 form, the device comprises three main elements, namely, a cylinder element, a transmission element, and a power element, the transmission element being of such nature that it will transform the rotary motion of the power element into re- 20 ciprocatoryr-motion 'to actuate a Vpiston in the cylinder element.

In this'embodiment ofthe invention, all three of ythese elements` are combined to produce a unitary-device or tool of compact and light- 25 weight construction. In case the invention is applied to other types of machin-ery, it may be necessary or advisable toutilze a separate power element,v v

The cylinder element comprises generally a 30 cylinder member housing a working piston and a floating hammer. The cylinder member is provided at one endrwith-a compression chamber, and at the other end with a tool chuck, which closes this end of the cylinder. Y 35 The compression chamber is provided with a packing box through which extends the piston rod attached to the piston. The pressure chamber is further v'provided with an intake valve throughwhich air is .drawn on each down stroke of the piston, andwhich automatically closes o-n each compression stroke. Y

The tool chuck'endfis providedwith suitable uncontrolled ports, and the cylinder is further provided with a port, at a point near the end of the ypiston travel andl whichl is open when the hammer isin itsfully downfpo'sition in contact with the end of the tool in the chuck. The arrangement of these ports .is such that on the up 50 .or `compression stroke, the 'fluid or air between the adjacent faces of the piston the hammer is rareiiedto such'an extent as to cause the hammer to v f cillov'- or trail the piston to a retracted position''where it may be acted upon by the com- 55 pressed air when released from the pressure chamber.

The compressed air in the pressure chamber is released to drive the hammer into engagement with the tool by means of a self-closing sleeve valve at the pressure chamber end of the cylinder, which controls a plurality of ports around the cylinder wall, which are uncovered by the piston at the end of its compression stroke. The sleeve valve is moved from its seat over the ports by the piston as it approaches the end of its back or compression stroke.

Upon the opening of the sleeve valve, the hammer is shot forward by the expansion of the compressed air. This movement of the hammer is followed by the piston, which causes fresh air to be drawn into the pressure chamber andcylinder through the intake port, while the used air is exhausted through the port in the cylinder which is uncovered by the hammer as it strikes the tool. Thus, a supply of fresh cool air is provided for each working cycle.

The transmission element comprises a casing suitably secured to the pressure chamber and which houses the mechanism for actuating the piston. The piston rod is secured to a crosshead mounted within the casing on suitable guides for sliding movement thereon. The crosshead is given a reciprocatory motion by meansl of two oppositely turning cranks suitably journalled in the sides ofthe casing which in this instance, are in the form of bevel gear Wheels oppositely disposed and in driving engagement with a common pinion driven by the power element, so that the bevel gears rotate in opposite directions at the same speed. A

The bevel gear wheels are provided with crank pins near their periphery, which engage sliding bearing blocks carried in slots on opposite sides of the crosshead in such manner that equal and balanced forces are impartedA to the crosshead throughout its whole range of movement. V

In this instance, the common pinion is keyed to the end of the motor shaft and the motor is suitably attached to the end of the transmission casing. The pinion may be driven by a separate power source, if desired.

Referring now to Fig. 1 of the drawings, I 0 designates the cylinder element, II the transmission element, and I2 the motor or power element.

The cylinder element I0 comprises a cylinder member I3 whichis provided at one end with a tool chuck I4 for holding a suitable tool I5, and at the other end, with a fitting I6 which forms a pressure chamber I1. Y

Within the cylinder there is provided a piston I8 and a floating hammer member I9y which functions, in a mannerrto be describedhereinafter, to subject the tool I5 to impact blows in order to accomplish the desired kind of work.

The piston I8 is attached to the working elements of the transmission element II by meansof the piston rod 2|, which extends through a suitable packing gland 22 formed in the tting I6.

In this instance, the hammer member I9 is actuated by compressed air, which is produced in the pressure chamber I1 on each back or com-Y pression stroke of the .piston I8 as it is reciprocated by the transmission element II and motor I2. The tool chuck I4, which closes one end of the cylinder, is provided with suitable open ports 23 and 24 and the cylinder is provided with a port 25, this arrangement being such that on 'the back stroke of the piston, the differencein air pressure on the opposite faces of the hammer causes it to trail the piston to a retracted position Where it may be subjected to a driving force by the compressed air in the pressure chamber.

The pressure chamber I1 is provided with a suitable air inlet valve 26 which functions on the down or expansion stroke of the piston to emit a fresh charge of air into the pressure chamber and cylinder through the ports 20 and which automatically closes on the compression stroke to seal the chamber.

In order to effect the release of the compressed air in the chamber I'I at the proper time to subjectrthe hammer I9 to a driving force, the end of the cylinder which extends within the pressure chamber I'I is provided with a plurality of openings or ports 21, which are normally held closed by a sleeve valve 28 that is self-closing by means of a coil spring 29.

The valve 28 is so constructed that it is actuated to its open position vto open the ports 2l by the piston I8 as it reaches or nears the end of its back stroke. In this instance, the valve 28 is provided with an integral collar portion 30, which extends to a point within the path of movement of the piston so that it engages the back face of the piston as it approaches the end of its back stroke. From this point until the piston reaches the end of its back stroke, the valve is actuated toward its open position against the force of` its biasing spring 29. 'Ihe ports 2l are so positioned that they are uncovered by the piston I 8 at or near the end of its back stroke, thus permitting the discharge of compressed air to enter the cylinder between the adjacent faces of the piston and the hammer. 'Ihis subjects the hammer to a sudden force, thus forcing it downward into engagement with the end of the tool I5, as shown.

In view of the foregoing, it will be apparent that the used air is discharged through the port 25 and a fresh charge of cool air is drawn in through the inlet valve 26, which automatically opens on the do-wn stroke of the piston. The expansion of the air in the cylinder provides a cooling effect upon the cylinder and working parts. The entrance of the fresh charge of air provides a further cooling effect and insures that there will always be a sufficient supply of air to properly actuate the hammer.

The piston I8 may be reciprocated in any suitable manner. However, in this embodiment of the invention, a. power transmission element II is provided, which is adapted to drive the piston in a straight-line motion, and which is of lightweight and compact construction in order that it may be attached directly to the cylinder element. The preferred form of transmission element comprises a gear casing 3|, which may be secured to a spacer sleeve 9 by suitable bolts 32. In order to give the piston I8 a straight-line motion, the piston rod 2I is connected to a crosshead 33, which is mounted within the casing 3I upon suitable guides 34 (see Fig. 2) in such manner that it may be reciprocated along the same line of movement as the piston.

In order to actuate the crosshead 33, the transmission element is provided with a pair of crank members 35 and 36, which in this instance, are in the form of bevel gear wheels mounted within the casing on opposite sides of the crosshead in suitable bearings, as shown.

As shown best in Fig, 1, the crosshead 33 is provided with longitudinal slots 31 on opposite sides thereof. The crank members 35 and 36 are connected to the crosshead by means of driving lugs 38,' which engage bearing blocks 39 slidably mounted in the crosshead slots. These bearing blocks slide back and forth in opposite directions Within the crosshead slots 37 as the cranks rotate, thus imparting a straight-line reciprocating movement to the crosshead and piston. The bearing blocks 39 may be in the form of rollers if desired.

It is apparent that the crosshead 33 may be actuated by the use of a single crank. However, in order that the crosshead will be subjected to balanced driving forces at all times and to reduce the Wear upon the guides 3d to a minimum, provision is made for actuating the cranks in opposite directions at the same speed. As will be understood with reference to Fig. 4, the rotation of the cranks in opposite directions causes the crank pins to move in a path designated by the circle, the diameter of which determines the piston travel. The relative position of the crank pins 38 is the same at all times, thus subjecting the crosshead to equal and balanced driving forces throughout its complete stroke.

In this instance, the cranks 35 and 33 are actuated by means of a single pinion gear 4B, which it attached directly to the shaft 4I of the motor I2. The motor frame 43 may be attached directly to the casing 3| by means of bolts 44, as shown.

Referring to 3, which is an enlarged view of the tool chuck I 4, it will be observed that it is provided with a longitudinal bore 45 which receives the end of the tool I5. The tool I5 is slidably mounted within the bore and is provided with a collar 45, which engages the end of the chuck,

The tool chuck I4 may be secured to the cylinder I8 in any suitable manner, such for ex-I ample, as by means of tie bolts 4'! extending through the lugs 138 on opposite sides thereof, as shown in Fig. 3. The tie bolts may be anchored in any desired manner (not shown) to the spacer sleeve I0, which is interposed between the fitting I6 and gear casing 3I. As will be readily understood, these tie bolts function to imite all of the parts between the spacer sleeve and tool chuck.

As shown in Fig. 5, the cylinder I3 may be provided vvith a plurality of exhaust ports 25 which are controlled by a spring loaded valve of any suitable type. As illustrated, the valve comprises a ring element 49 surrounding the cylinder which is biased to a closed position by springs 5 carried in suitable openings in the end of the tool chuck I4.

As will be readily understood, the valve ring lie will be positively closed when the piston I8 reaches the end of its stroke and before the hammer I9 reverses its direction of movement.

The invention as disclosed provides an emcient light-weight and compact tool of the pneumatic type, which is electrically operated. The principles of this invention may be applied to tools of dierent form, which in some cases, may have a separate or independent driving element, in which case the transmission element I I may be actuated from a common power source in the form of an engine by means of a flexible shaft or other suitable means.

It is apparent that a device of the kind described possesses many advantages over other forms of pneumatic percussion tools now in common use, In addition to its light weight and v compact construction, it may be supplied with power from any suitable source of electrical energy through an insulated cable and used with the same ease and flexibility as motor operated drills and the like are now used.

It is so constituted that it inherently functions to supply its own compressed air, thus entirely eliminating the use of air compressors and air hose.

The efficiency is relatively high as compared to the older types of pneumatic percussion tools, for the reason that the air is compressed and expanded within the same cylinder. 4The compression chamber receives a full charge of fresh air on each stroke of the piston and is tightly sealed by the valves and piston during the compression period. Thus, there are no leaks and no deficiency in the air supply. The drop in temperature of the air during the expansion thereof assists in cooling the cylinder and other parts.

It may be stated, in conclusion, that while the illustrated and described example constitutes a practical embodiment of my invention, I do not Wish to limit myself strictly to the exact details herein illustrated, since modifications of the same may be made without departing from the spirit of the invention, as defined in the appended claims.

I claim as my invention:

1.. In a fluid-pressure driven tool, in combination, a cylinder, a working piston therein, power means having a rotating element for driving the piston, a slidably mounted crosshead attached to the piston, a pair of rotatable cranks mounted on opposite sides of the crosshead on a common axis of rotation and in driving engagement with the crosshead, and gear means connecting the said cranks to the rotating element of the power means whereby the cranks are driven in opposite directions simultaneously.

2. In a fluid pressure driven tool, in combination, a cylinder, a working piston therein, a motor for driving the piston, a crosshead secured to the piston and mounted for reciprocatory movement therewith, a pair of gear wheel cranks disposed in driving engagement with the crosshead and rotatably mounted on a common axis on opposite sides thereof, and a gear driven by the motor and disposed in driving engagement with the gear cranks for driving said gear cranks in opposite directions simultaneously.

3. In a fluid pressure driven tool, in combination, a cylinder, a working piston therein, a motor for actuating the piston, a crosshead, a piston rod interposed between the crosshead and piston, guides for slid'ably supporting the crosshead for reciprocatory motion in line with the piston, a pair of crank members rotatably mounted on a common axis of rotation on opposite sides of the crosshead and disposed in driving engagement with the crosshead, gear teeth on each of said crank members forming gear Wheels thereof, and a pinion gear mounted on the end of the motor shaft and engaging the gear teeth on each crank member whereby on rotation of the motor the crank members are simultaneously rotated in opposite directions to impart balanced driving forces to the crosshead.

4. In a fluid pressure driven tool, in combination, a cylinder, a working piston therein, a motor for driving the piston, a crosshead attached to the piston and mounted for reciprocatory movement therewith, said crosshead having longitudinal slots on opposite sides thereof, a bearing member slidably mounted in each slot, a pair of cranks rotatably mounted on a common axis on opposite sides of the crosshead and engaging the bearing members in the crosshead slots, and driving means connecting the cranks to the motor shaft operable to cause said cranks to be driven simultaneously in opposite directions in response to the rotation of the motor shaft thereby to reciprocate the crosshead by the application thereto of balanced driving forces.

5. In a fluid pressure-driven mechanism, in combination, a working piston, a motor for actuating the piston, a crosshead secured to the piston, and means comprisingoppositely rotating gears provided with lugs engaging the crosshead and mounted on a common axis driven by the motor for imparting a reciprocatory motion to the crosshead and piston.

6. In a fluid pressure-driven mechanism, in combination, a cylinder, a working piston in the cylinder, a crosshead attached to the piston, said crosshead being mounted for reciprocatory movement and having an elongated recess on opposite sides thereof, a pair of gears mounted for rotation about a common axis and provided with driving lugs engaging said recesses, and means for rotating the gears in opposite directions at the same speed to reciprocate the crosshead and piston.

'7. In a iiuid pressure-driven mechanism, in combination, a cylinder, a working piston in the cylinder, a crosshead attached to the piston, said crosshead being mounted for reciprocatory movement and having an elongated recess on opposite sides thereof, a pair of gears mounted for ri tation about a common axis on opposite sides of the crosshead and in planes parallel to the path of movement of the crosshead, said gears having driving lugs engaging the recesses in the crosshead, and means for simultaneously driving the gears in opposite directions.

8. In combination, a piston, a crosshead attached to the piston and mounted for reciprocatory movement in the san'ie plane of movement as the piston, said crosshead having oppositely disposed longitudinal slots on opposite sides thereof, a pair of cranks mounted for rotation on a common axis engaging said slots in the crosshead and adapted when rotated in opposite directions to reciprocate the piston, and motor operated means for driving the cranks in opposite directions at the same speed.

9. In a power actuated pneumatic hammer, in combination, a cylinder having a piston therein, a power transmission casing attached to one end of the cylinder, a crosshead mounted in the casing for reciprocatory movement in line with the movement of the piston and having longitudinal slots on opposite sides thereof, means for attaching the piston to the crosshead, a pair of cranks mounted within the casing engaging said slots in the crosshead and disposed to rotate in opposite directions on a common axis to reciprocate the crosshead, and means including a motor attached to the casing opposite the cylinder for driving the cranks in opposite directions at the same speed.

10. In a fluid pressure-actuated tool, in combination, a cylinder, a piston and a floating hammer in the cylinder, means for reciprocating the piston, a pressure chamber at one end of the cylinder, and a spring biased valve controlled by the action of the piston for releasing the Huid-pressure from the pressure chamber into the cylinder between the adjacent faces of the piston and hammer to actuate the oating hammer.

11. In` a ii'ui'd pressure-actuated tool, in combination, a cylinder, a piston and a floating hammer in the cylinder, means for reciprocating 'the piston, a pressure chamber at one end of the cylinder, and a valve operable to release the fluidpressure of the pressure chamber into the cylinder to drive the hammer, said valve being actuated to the open position by the piston at a predetermined position of its travel.

12. In a fluid pressure-acuated tool, in cornbination, a cylinder provided at one end with a tool holding chuck and at the opposite end with a pressure chamber, a working piston and a oating hammer in the cylinder, means for reciprocating the piston, and mechanical Valve means actuated in accordance with the piston position for releasing the fluid pressure of the pressure chamber into the cylinder in front of the hammer.

13. In a fluid pressure-actuated tool, in combination, a cylinder provided at one end with a tool holding chuck and at the opposite end with a pressure chamber, a Working piston and a floating hammer in the cylinder, means for reciprocating the piston, a self-closing valve operable to release the fluid pressure of the pressure chamber into the cylinder, and means whereby the valve is actuated to the open position by the piston at the end of its compression stroke to release the said fluid pressure into the cylinder between the adjacent faces of the piston and hammer to subject the hammer to an actuating pressure.

14. In a power-driven pneumatic tool, in combination, a cylinder housing a working piston and a floating hammer, means for reciprocating the piston, a pressure chamber at one end of the cylinder, a self-closing intake valve in the pressure chamber, and a self-closing valve actuated by the piston at or near the end of its compression stroke for releasing the pressure into the cylinder to actuate the hammer from a retracted to an impact position.

15. In a power-driven pneumatic tool, in combination, a cylinder housing a working piston and a floating hammer, means for reciprocating the piston, a pressure chamber at one end of the cylinder, a plurality of ports interconnecting the cylinder and the pressure chamber, said ports being so located as to be uncovered by the piston at the end of its compression stroke, a self-closing sleeve valve covering said ports, said valve being d opened by the piston near the end of its compression stroke, thereby to release the fluid pressure into the cylinder between the adjacent faces of the piston and hammer to drive the hammer to an impact position.

16. In a power-actuated pneumatic hammer, in combination, a cylinder, a piston and a oating hammer mounted to reciprocate within the cylinder, means for reciprocating the piston to compress a charge of air and exert a retracting influence upon the hammer, a compression chamber closing one end of the cylinder, and a valve mechanically actuated by the piston near the end of its compression stroke for releasing the compressed air from the compression chamber into the cylinder between the piston and hammer to impart a driving force to the hammer at the end of each compression stroke of the piston.

17. In a power-actuated pneumatic hammer, in combination, a cylinder, a piston and a floating hammer mounted to reciprocate within the cylinder, a motor, a power transmission element interposed between the motor and cylinder for transforming the rotary motion of the motor into reciprocatory motion to actuate the piston, said motor, transmission element and cylinder being joined together to form a unitary structure, a pressure chamber at one end of the cylinder for receiving and holding a charge of air compressed by the piston, said hammer being disposed to trail the piston on its compression stroke, and a valve mechanically operated in response to the piston reaching the end of its compression stroke for releasing the charge of compressed air into the cylinder between the adjacent faces of the piston and hammer to impart a driving force to the floating hammer.

18. A power-driven pneumatic tool comprising, a cylinder provided at one end with a tool chuck and at the opposite end with a pressure chamber having a discharge valve, a piston and a floating hammer within the cylinder, said piston having a retracting inuence on the hammer on its compression stroke and functioning to mechanically actuate the discharge Valve to actuate the hammer, a casing attached to the cylinder, a crosshead mounted within the casing for reciprocatory movement in line with the piston, said crosshead having longitudinal slots on opposite sides thereof, a piston rod for attaching the piston to the crosshead, a pair of bearing blocks disposed for sliding movement in the crosshead slots, a pair of cranks journalled Within the casing on a common axis on opposite sides of the crosshead, said cranks engaging the bearing blocks and adapted when rotated in opposite directions to reciprocate the crosshead and piston, and means including a motor attached to the casing for driving the cranks in opposite directions at equal speeds, thereby to subject the crosshead to balanced driving forces at all times.

ALEXANDER PALMROS. 

